To find the total mass of the 28 boxes of cereal, you should use the equation:
\[ 28 \times 375 = m \]
Now, let's calculate the total mass \( m \):
\[ m = 28 \times 375 \]
Calculating that:
\[ m = 28 \times 375 = 10,500 \text{ grams} \]
So the correct response is:
28 × 375 = m; m = 10,500 grams